Conventionally, a crystal of ammonium carboxylate is produced by a well-known method using (a) a crystal of carboxyl acid and (b) amine.
For example, inventors of the present invention reported that a crystal of muconic alkylammonium is obtained as follows. A crystal of muconic acid and normal alkylamine are dissolved and mixed in a solvent such as methanol, water, or the like. Then, the solvent is removed, and a solid substance thus obtained is recrystallized.
The inventors of the present invention also reported that a polymer crystal is produced by solid-state polymerization, i.e. by radiating light, X-rays, γ-rays, or the like onto the crystal of muconic alkylammonium obtained by the foregoing method, and that a layered crystal of polymuconic acid is obtained by hydrolyzing the polymer crystal with acid, and then removing the solvent.
The inventors of the present invention further reported that, by the following operation, normal alkylamine is intercalated between layers of the layered crystal of polymuconic acid obtained by the foregoing method: (1) dispersing the layered crystal in a dispersion medium such as methanol, water, or the like, (2) mixing the solution with normal alkyl amine, and (3) removing the dispersion medium.
However, according to the conventional methods using a solvent or a dispersion medium, a polymer crystal having a layered structure cannot be obtained in a simple manner, because it is necessary to separate the solvent or the dispersion medium, and to cause recrystallization.
Moreover, according to the method in which intercalation is induced by using a dispersion medium, there are cases in which a polymer crystal having a layered structure cannot be obtained, because a polymer crystal swells or dissolves in the dispersion medium if certain kind of amine is used. Especially, if alkyl primary amine having a branch structure or primary amine including a functional group is used, a polymer crystal in which the alkyl primary amine having a branch structure between layers of a layered crystal or the primary amine including a functional group cannot be obtained, because the layered crystal of polymuconic acid swells or dissolves in the dispersion medium during a reaction.
Existence of photoresponsive low-molecular-weight compounds, photoresponsive polymers, and photoresponsive polymer materials are conventionally well-known. For example, it is well-known that an azobenzene derivative (a low-molecular-weight compound) has photoresponsiveness, i.e. that an azobenzene derivative is isomerized into a cis body when subjected to ultraviolet rays, and into a trans body when subjected to heat or visible light. Also well-known are photoresponsive polymers in which a side chain thereof is chemically bonded with a substituent including an azo group, and photoresponsive polymer materials in which a low-molecular-weight azo compound is dispersed in a polymer matrix. These are used in a solution state or in a film-shaped solid state.
Many attempts have been made to intercalate amine including a photoresponsive group, such as an azo group, into a generally available inorganic layered crystal. It is well-known that, because some inorganic layered crystals, namely clay minerals, silicate, and metal oxide, have cation exchangeability due to negative charges thereof, it is relatively easy to intercalate amine into these inorganic layered crystals, i.e. clay minerals, silicate, and metal oxide (see Chemical Society of Japan ed, “Inorganic and Organic Nano Compounds”, in Kikan Kagaku Sousetsu, No. 42, Gakkai Shuppan Center (1999), p. 33-44). For example, it is reported that in one case amine including an azo group was intercalated into an inorganic layered crystal (For example, “Photocontrol of the Basal Spacing of Azobenzene-Magadiite Intercalation Compound”, M. Ogawa, T. Ishii, N. Miyamoto, K. Kuroda, Adv. Mater. 13, 1107-1109 (2001), and “Preparation of a Cationic Azobenzene Derivative-Montmorillonite Intercalation Compound and the Photochemical Behavior”, M. Ogawa, Mater. Chem., 8, 1347-1349 (1996)).
However, it is not easy to photoisomerize a usual azobenzene derivative (which includes no amino group) and induce a structural change of a crystalline polymer by mixing the azobenzene derivative and the crystalline polymer. Moreover, it requires considerable time and effort to chemically bond an azo group with a polymer directly. Therefore, the conventional photoresponsive polymer cannot be manufactured easily, let alone with variations. Moreover, sufficient stability and a sufficient function (photoresponsiveness) cannot be attained by simply dispersing a low-molecular-weight azo compound in a matrix.
Moreover, it is not easy to use, in a solution state or in a film-shaped solid state, a photosensitive material in which amine including a photoresponsive group, such as an azo group, is intercalated in an inorganic layered crystal. Therefore, such a photosensitive material has a drawback that they can be used only for limited purposes.
A well-known photofunctional polymer other than the photoresponsive polymers and the photoresponsive polymer materials is a conjugated system polymer that absorbs light of a certain wavelength band. For example, crystalline polydiacetylene obtained by polymerizing diacetylene is a colored conjugated system polymer that has high absorbance with respect to light in a visible region.
Incidentally, in order to design a crystalline polymer such as polydiacetylene, topochemical polymerization is performed. Well-known examples of the topochemical polymerization are polymerization of a 1,3-diene monomer such as a muconic derivative, a sorbic derivative, or the like, and polymerization in a built-up film such as an LB (Langmuir-Blodgett) film or the like. The topochemical polymerization is one form of solid-state polymerization. In the topochemical polymerization, a reaction proceeds with minimum movements of atoms and substituents, while a center of gravity of a monomer and symmetry of a crystal are maintained. Therefore, a structure of a product obtained by the topochemical polymerization is controlled not only by chemical properties, e.g. reactivity, of the monomer, but also by an arrangement of the crystal formed by the monomer. Thus, in the topochemical polymerization, a polymerization reaction proceeds under a control of a crystalline lattice. Therefore, the topochemical polymerization makes it possible to design a polymer having stereospecificity and stereoselectivity.
However, according to the conventional topochemical polymerization of diacetylene, it is not easy to predict reactivity of the polymerization reaction. Therefore, it is not easy to predict a crystalline structure of the polydiacetylene obtained by performing the topochemical polymerization. In other words, it is not easy to control an arrangement of polymer chains in the crystal of the polydiacetylene. Therefore, because the crystalline structure of the polydiacetylene obtained by performing the topochemical polymerization varies according to various conditions such as a condition of polymerization and the like, it is not easy to obtain polydiacetylene having an intended absorbing property.
On the other hand, if the polydiacetylene is used as a photofunctional polymer, it is desired that the polydiacetylene have a certain crystalline structure under a certain reaction condition, in order to attain a stable function. It is therefore desired that an arrangement of the polymer chains of the polydiacetylene obtained by polymerizing diacetylene be controlled, so as to obtain polydiacetylene that has a certain absorbing property. If such polydiacetylene that has an intended absorbing property cannot be attained with high reproducibility by setting a reaction condition, it is not easy to use the polydiacetylene as a photofunctional polymer.
The present invention was made to solve the foregoing conventional problems. An object of the present invention is therefore to provide a photoresponsive polymer in which amine including an azo group, which is a photoresponsive group, is intercalated as a guest compound in a layered crystalline polymer including carboxyl acid, the photoresponsive polymer being such that an absorbing property and a structure thereof can be changed by radiating light so as to cause cis/trans isomerization of the azo group. Another object is to provide a built-up type diacetylene polymer that includes polydiacetylene having a layered structure in which an arrangement of polymer chains in a crystal is controlled, the built-up type diacetylene polymer being a conjugated system polymer having high absorbaption in a visible region. Yet another object is to provide a crystal of ammonium carboxylate made of carboxyl acid and at least one nitrogen-containing compound selected from the group consisting of amine and ammonia, and to provide a method of manufacturing a crystal of ammonium carboxylate suitable for manufacturing the photoresponsive polymer and the built-up type diacetylene polymer.